The present invention relates to a sound effector for use with electronic or electric musical instruments such as music synthesizers, electric guitars or the like, and more particularly to a technique of imparting a distortion effect to a sound by digital signal processing. The present invention further relates to a multi-effector that is capable of selectively imparting plural effects by itself, and more particularly to an improvement in on/off switching control over plural effects using an effect bypass function.
In some music areas such as rock, it has been conventionally known to distort the output signals of an electric guitar through specific distortion circuitry, so as to create peculiar guitar sounds. Traditionally, such a distortion effect was achieved using nonlinear amplification characteristics of vacuum tube amplifiers, and then in later years, the age was experienced when the distortion effect was achieved using transistor circuitry. In recent years, however, it has become more and more popular to impart a distortion effect to a sound on the basis of digital signal processing.
According to the known distortion effect imparting technique based on digital signal processing, the output signals of an electric guitar are converted into digital data, and then the digital data are amplified by a predetermined amplification factor. Then, all of the digital data in excess of a predetermined maximum bit number (for example, 16 bits) as the result of the amplification are subjected to a so-called clipping process, by which they are treated as data of a maximum value. In FIG. 8, there are shown an example of nonlinear characteristics achieved by such a clipping process.
In the case where the effect impartment is done by digital signal processing, necessary calculations can be performed very accurately, with almost no characteristic errors caused by various components employed. Thus, the prior distortion effect device, as will be readily seen from FIG. 8, amplifies the digital data in a complete linear manner over a certain central region and then clips the data abruptly. Such characteristics tend to result in stiff, hard tone colors, which never provide mild, rich sounds that used to be provided by the natural component characteristics of the traditional vacuum tubes in an amplifier device. As the result, the distortion effect based on the digital processing has been never been satisfactory.
In addition, a multi-effector device has also been developed which is capable of achieving plural effects by itself. Among such plural effect functions assigned to the multi-effector device, compressor, distortion, chorus, flanger and reverberation may perhaps be the most popular. In general, an on/off switch for each of these effect functions is provided on the body or foot controller of the effect or device so that on/off control over each effect function can be performed independently of the other functions. Such a multi-effector device is also known which has an effect bypass function such that all assigned effect functions can be cancel led by operating the effect bypass switch, so as to allow input signals to be output with no particular effect imparted thereto.
However, with the effect bypass function of the prior multi-effector device, it is only possible to make a choice as to whether all the effect functions should be cancelled, i.e., bypassed, or all the effect functions (except such function having been turned off, namely, made ineffective by the on/off switch) should be turned on, namely, made effective. Thus, if it is desired to turn on only plural specific effect functions (for instance, compressor and distortion) selected from among a greater number of available functions (so to speak, not-all plural effect functions), it is necessary for the user to operate the respective on/off switches of the selected effect functions; in other words, the on/off switch operation must be made at least two times. Because, in ordinary cases, effect function switching operation has to be done during a performance very quickly (for instance, within one breath period), such plural operations of the on/off switches can undesirably disturb the performance.